This invention relates to vegetable oils that contain an altered fatty acid content, more particularly, an elevated stearic acid content and a decreased polyunsaturates content.
Cocoa butter is dominated by three fatty acids, palmitic, stearic and oleic acid, and three triacylglycerols (TAGs) containing these particular fatty-acids. Approximately 80% of the TAGs within cocoa butter are palmitate-oleate-palmitate (13-19%), palmitate-oleate-stearate (36-42%), and stearate-oleate-stearate (23-29%). Since cocoa butter is expensive, and its supply is limited, various alternatives have been proposed. Cocoa butter replacers are typically derived from partially hydrogenated, or partially hydrogenated and fractionated blends of soybean, canola, and palm oils. As such, these oils have a high amount of trans fatty acids. See, for example, Bailey""s Industrial Oil and Food Products, Fifth Edition, John Wiley and Sons, Inc., Vol. 4, pp. 384-389 (1996).
Cocoa butter substitutes generally contain lauric acid as a main component (40-50%), and are typically derived from the oil and coconut palm. Genetic engineering has led to other plant sources having elevated levels of lauric acid. For example, U.S. Pat. No. 5,344,771 describes transgenic Brassica plants that produce canola oil that is rich in lauric acid.
Cocoa butter equivalents and extenders have a TAG composition that is similar to cocoa butter. Cocoa butter equivalents are derived from palm, illipe, shea, sal and kokum fats. Attempts to create other cocoa butter equivalents from oilseed plants have not been successful. For example, U.S. Pat. No. 5,723,595 describes transgenic Brassica plants that contain a delta-9 desaturase transgene. Oils extracted from these plants have increased amounts of stearic acid, but also contain increased amounts of linolenic acid and/or increased levels of long chain and very long chain fatty acids (18 carbons or greater).
Brassica plant lines with reduced levels of linolenic acid (2.5-5.8%) and elevated levels of oleic acid (73-79%) have been described (Pleines et al., Fat Sci. Technol., 90:167-171, 1988). Although there are certain problems associated with selecting mutant plants that have an altered content of linoleic and linolenic acids (Rakow et al., J. Amer. Oil Chem. Soc., 50:400-403, 1973), Stellar summer rapeseed oil that contains 3% linolenic acid and 28% linoleic acid has been reported (Can. J. Plant Sci., 68:509-511, 1988). In addition, a reconstituted line characterized by low linolenic and high linoleic content was produced by gene transfer in an interspecies cross from Brassica juncea into Brassica napus (Roy et al., Z. Pflanzenzuchtg, 95:201-209, 1985). Prospects for the development of Brassica napus having improved linolenic and linoleic acid content also have been reported (Roy et al., Plant Breeding, 98:89-96, 1987). Seeds and oils having 79% oleic acid and 3.5% xcex1-linolenic acid also have been reported (European Patent application 323 751).
The invention features vegetable oils that have an elevated stearic acid content and a decreased polyunsaturated fatty acid content when compared with known vegetable oils.
In one aspect, the invention features an endogenous oil extracted from plant seeds that has a stearic acid content of about 15% to about 30% (e.g., 17% to about 28%) and a polyunsaturated fatty acid content of about 2% to about 15% (e.g., about 2% to about 6%). The oil can have an xcex1-linolenic acid content of about 0.6% to about 2.0% and/or a palmitic acid content of about 6% to about 20%. For example, the oil can have a palmitic acid content of about 7% to about 19%. The oil can have an oleic acid content of less than about 64%, e.g., about 46% to about 53%. The iodine value of such oils is less than about 76. Oils of this embodiment can have a differential scanning calorimetry (DSC) melting point of about 4xc2x0 C. to about 20xc2x0 C. in the absence of cold storage crystallization and a DSC melting point of about 24xc2x0 C. to about 40xc2x0 C. following cold storage crystallization. The endogenous oil can be extracted from Brassica seeds.
In another aspect, the invention features an oil having a stearic acid content of about 19% to about 30% and a polyunsaturated fatty acid content of about 2% to about 15%. Such an oil further has a palmitic acid content of about 6% to about 19% and/or an oleic acid content of about 46% to about 53%. An oil of this embodiment has a DSC melting point of about 30xc2x0 C. to about 40xc2x0 C. in the absence of a cold storage period. About 15% or more of the TAGs in the oil (e.g., about 18% or more or 30% or more) include an oleate moiety at the sn-2 position and palmitate or stearate moieties at the sn-1 and sn-3 positions. About 10% to about 25% of the TAGs in the oil can have a stearate moiety at the sn-1 position, an oleate moiety at the sn-2 position, and a stearate moiety at the sn-3 position; and about 6% to about 12% of TAGs in the oil can have a palmitate moiety at the sn-1 position, an oleate moiety at the sn-2 position, and a stearate moiety at the sn-3 position.
The invention also features a vegetable oil, wherein at least about 15% of the TAGs in the oil include an oleate moiety at the sn-2 position and palmitate or stearate moieties at the sn-1 and sn-3 positions. For example, at least about 18% or at least about 30% of the TAGs can include an oleate moiety at the sn-2 position and palmitate or stearate moieties at the sn-1 and sn-3 positions.
In another aspect, the invention features a method of producing a vegetable oil. The method includes crushing seeds produced by a plant (e.g., a Brassica plant), wherein the seeds have a stearic acid content of about 15% to about 30% and a polyunsaturated fatty acid content of about 2% to about 15%; and extracting an endogenous oil from the crushed seeds. The Brassica plant can exhibit reduced delta-9 desaturase activity and reduced delta-12 desaturase activity, and increased stearoyl acyl-ACP thioesterase activity. The Brassica plant further can exhibit a reduced delta-15 desaturase activity. The endogenous oil can have a palmitic acid content of about 6% to about 20%. The method further can include the step of fractionating the endogenous oil into a stearine fraction and an olein fraction, wherein the stearine fraction has a stearic acid content of about 20% to about 30% and an oleic acid content of about 46% to about 53%.
In a further aspect, the invention features a confectionery product that includes a fat component, wherein the fat component includes a vegetable oil having a stearic acid content of about 20% to about 30% and a polyunsaturated fatty acid content of about 2% to about 15%. The vegetable oil further can have an oleic acid content of about 46% to about 53%. The invention also features a confectionery product that includes a fat component, wherein at least about 18% of the TAGs in the fat component include an oleate moiety at the sn-2 position and palmitate or stearate moieties at the sn-1 and sn-3 positions. The fat component can be derived from canola, soy, corn, or sunflower.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used to practice the invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. Other features and advantages of the invention will be apparent from the following detailed description, and from the claims.